Processes for treating polyamides

ABSTRACT

The invention provides a process for improving the textile properties of natural polyamide fibres in which the fibres are treated with liquid ammonia. The fibres can be treated in various forms, including finished or knitted materials. The treated products have various improved properties such as improved feel and elasticity or crimp.

United States Patent 11 1 Dalle [4 1 Sept. 16, 1975 PROCESSES FOR TREATING POLYAMIDES [75] Inventor: Jean-Paul Dalle, Saint-Quentin,

France [73] Assignee: Societe Anonyme dite: Cmnium de Prospective Industrielle S.A., Saint-Amand, France [22] Filed: Mar. 14, 1973 [21] App]. No.: 341,291

[30] Foreign Application Priority Data Mar. 14, 1972 France 72.08875 [52] US. Cl 8/128 R; 8/l27.5; 8/127.5l; 8/127.6

[51] Int. CI. D06M 3/02; D06M 13/00;

D06M 3/00; A61K 7/06 [58] Field of Search.... 8/125, 127.5, 127.51, 127.6,

[56] References Cited UNITED STATES PATENTS 1,989,098 l/l935 Lilienfeld 8/125 1,998,551 4/1935 Mahn 8/125 2,509,549 5/1950 Woodell 8/125 3,406,006 10/1968 Lindberg et al. 8/125 3,511,591 5/1970 Webb 8/125 FOREIGN PATENTS OR APPLICATIONS 592,880 10/1947 United Kingdom 8/128 R Primary Examiner-Benjamin R. Padgett Assistant Examiner-T. S. Gron Attorney, Agent, or FirmLewis H. Eslinger; Alvin Sinderbrand [5 7] ABSTRACT 7 Claims, No Drawings PROCESSES FOR TREATING POLYAMIDES This invention relates to processes for treating natural polyamides in particular polypeptides. The present invention will be specifically described in relation to treating polypeptides althoughit can be used for treating natural polyamides.

It has hitherto been proposed to treat spun or woven cellulosic fibres in order to improve certain of their properties, notably their resistance to stretching and their affinity for dyes. It has been proposed, .for example, to effect mercerising in which the cellulosic fibres are treated with liquid ammonia. However, in order to obtain preferred results with cellulosic fibres, it is necessary to observe certain precautions and modes of operation during passage of the fibres or weave through the liquid ammonia. In particular, the time of contact of the fibres with the ammonia should be short, of the order of a second, and furthermore, the fibres or weave must be capable of withstanding high mechanical tension during their treatment, the tension beingas near as possible to the elastic limit of the fibres. The removal of the ammonia is effected using water or steam. After the treatment, the lengths of the fibres or of the weave are greater than their initial lengths. This corresponds to an increase in the metric count or size in the case of a fibre. Using this process, the fibres are provided with an improved lustre and smoothness and they become more compact and more resistant. Their elasticity practically disappears and their stability is improved.

According to the present invention there is provided a process for improving the textile properties of natural polyamide fibres, which process comprises contacting the fibres with liquid ammonia at a temperature and for a time whereby their textile properties are improved.

Further according to the present invention there is provided a process for improving the textile properties of polypeptide fibres which process comprises contacting the fibres with liquid ammonia at a temperature and for a time whereby their textile properties are improved.

The prese nt invention can be used with advantage for the treatment of wool. The improved properties of the natural polyamide fibres after treatment are unexpect ed because natural polyamide fibres have a structure which is totally different from the polysaccaride structure ,of, cellulosic fibres.

Natural polyamide fibres may, for example, be in the form of a flock, threads,-finished articles, woven or knitted materials, or any other form. r

The process may, for example, be effected by impregnation, or by immersion of the fibres in a bath of liquid ammonia maintained at, .33C at atmospheric pressure. The treatment may also be effected ata temperature above -33C (the boiling temperature of ammonia at atmospheric pressure)but at an elevated pressure, for example-6 atmospheres at C. If desired, the ammonia for the treatment can include a'diluent, a dressing agent, a softening agent, a dye, etc. The process can be effected continuously or discontinuously and, it can be adapted toproduc'e preferred characteristics and properties in the treated fibres. ltiis generally easy to untangle wool or other polypeptide fibres after reaction with liquid ammonia. Drying at a temperature above the boiling point of liquid ammonia is generally sufficient.

Improvements in the properties of the fibre characteristics are generally only permanent if the contacting with liquid ammonia is effected for more than a certain time, which usually depends on the operating conditions. If the contacting is effected, for example at -33C, and at atmospheric pressure, the lower limit is of the order of 1 minute.

The feel of the fibres and articles after treatment is generally firmer as the length of treatment is increased, so that the dynamometric resistanceand the elasticity of the fibres or articles noticeably increase as a function of the length of treatment. However, they remain unchanged beyond an upper limit. This limit depends on the material being treated and onthe process conditions. It is usually, for example, of the order of 40 minutes for a treatment at -33C at atmospheric pressure. Finally, the process can increase the dye affinity of the fibres, whatever the form of product.

When the polypeptide is in the form, for example, of filaments or finished articles, and the desired effect is an increase in elasticity or crimp, it is generally preferred that no tension be applied to the fibres during the treatment. Indeed, it is preferred to allow a relaxation of the filaments or finished articles to occur. It is also preferred that the filaments or the finished articles, weaves or knitted materials, be continuously moved during their treatment with ammonia, and that their speeds of entry into the apparatus or treatment bath is above their exit speed.

These measures generally enable improved polypeptide fibres to be produced. The filaments and finished articles generally have a bulky appearance and a considerable resilience. Furthermore, the treatment improves the unfelting of the articles as well as their resistance to shrinkage on washing. The method in accordance with the invention can also be used for mixtures of fibres.

Modifications of the properties of polypeptide fibres by using liquid ammonia, are more or less permanent, after elimination of treatment liquid according to the duration of the treatment. A

Although' the Applicants do not wish to be bound by theory, it is believed that the ammonia has a preferential action on the orthocortex of the fibres and results in a differentiation between the orthocortex and the paracortex, thereby producing the improved properties.

By way of example, experiments have been effected on various forms of wool, by immersion for various times in a bath of liquid ammonia at -33C and atmospheric pressure. Removal of the liquid ammonia was effected by. drying in the open air at ambient temperatures.

Various tests were effected to determine the properties of the treated products, the characteristics of which being given below.

EXAMPLE I a. Estimation of dimentional changes '4. B: Treated unbleached C: Non-treated dyed Relaxatlon Shrmkage Total D: r a g f r minutes stitch direction 12.3% 3.1% 15.4% A transverse direction 3.4% 1.7% 5.1% Contraction 1 1 area 15.7% 4.8% 20.5 sample stitch direction 1.8% 1.1% 0.7% A1 241 B transverse direction l.3% 1.9% 3.2% B; 318 degree of contraction: area 0.5% 3% 2.5% 0

stitch direction O.3% 1.1% 0.8% D: 336 degree of contraction: 28.4% C transverse direction 1.4% 2.3% 3.7%

area 17% 11% 29% b. compressibility D stitch direcion 1?? r 5g of filaments were compressed to a density of 255 transverse lrectlon c a z- 3 area 02% 13% 15% kg/m and the resistance was measured in kilograms.

Coefficient of compression Sag tests Compression Resistance measured optically with the aid of an eclatometer, a Sample was Air Relaxed Water Relaxed Air Relaxed Water Relaxed formed with a 10 mm projection and the depth of the A 294 372 16.7 14.0 resulting spherical depression was measured with a 2 3'1; '23; 3-3 g-g cathetometer, immediately after the test and after 24 D 1 hours.

EXAMPLE 4:

Immediately 24 hours Double knit jersey treated for 60 minutes Non-treated 23.3 20 Treated 30 mins 1 1.6 10.3 Treated 90 mins 14 9.6 Non-treated Treated Variation 71 30 Weight (g/m") 310 450 45.1 Resistance to breakage (lbs/ 82 82 EXAMPLE 2: Abrasion resistance (number of rubs) 15,000 33,000 120 Unbleached combed ribbon. Elasticity w n 54 43 20.4 2 (/c) courses 58 42 27.6 A Non treated Extensibility (/c) wales 7 4 42.9 B: Treated for 60 minutes 70 courses 5 4 200 a. Contraction Sample Equivalent properties can be obtained by treating :A: 19.5 g/m other polypeptide fibres such as mohair or rabbit hair. :B: 29.5 g/m Iclaim:

The treatment thus gave a contraction of 34%. The extension of the fibres shows a super-contraction of about 10%. The following table gives the results of tests of the almeter. 45

71 at 20 min at 30 min at 40 min at min b. Degree of crimp and compressibility A: 2.88 crimps per cm.

EXAMPLE 3:

Part-combed thread.

A: Non-treated unbleached 1. A process for improving the properties of textiles consisting essentially of natural polyamide fibres, which process comprises contacting the fibres with liquid ammonia at a temperature and for a time whereby their textile properties are improved.

2. A process according to claim 1, wherein the fibres are in the form of a wad, a thread, or a woven or knitted material.

3. A process according to claim 1, wherein the fibres are of wool.

4. A process according to claim 1, wherein the contacting with ammonia is efi'ected at about 3 3C at atmospheric pressure for at least 1 minute.

5. A process according to claim 3, wherein the contacting is effected at about 33C at atmospheric pressure for at least 1 minute.

6. A process according to claim 1, wherein the fibres are in the form of filaments, or woven or knitted materials and the contacting is effected without stretching of the fibres.

7. A process according to claim 6, wherein the treatment is effected with continuous displacement of the fibres, the speed of entry thereof into the liquid ammonia is greater than the speed of exit therefrom so as to compensate for contraction of the fibres as a result of the treatment. 

1. A PROCESS FOR IMPROVING THE PROPERTIES OF TEXTILES CONSISTING ESSENTIALLY OF NATURAL POLYAMIDE FIBERS, WHICH PROCESS COMPRISES CONTACTING THE FIBERS WITH LIQUID AMMONIA AT A TEMPERATURE AND FOR A TIME WHEREBY THEIR TEXTILE PROPERTIES ARE IMPROVED.
 2. A process according to claim 1, wherein the fibres are in the form of a wad, a thread, or a woven or knitted material.
 3. A process according to claim 1, wherein the fibres are of wool.
 4. A process according to claim 1, wherein the contacting with ammonia is effected at about -33*C at atmospheric pressure for at least 1 minute.
 5. A process according to claim 3, wherein the contacting is effected at about -33*C at atmospheric pressure for at least 1 minute.
 6. A process according to claim 1, wherein the fibres are in the form of filaments, or woven or knitted materials and the contacting is effected without stretching of the fibres.
 7. A process according to claim 6, wherein the treatment is effected with continuous displacement of the fibres, the speed of entry thereof into the liquid ammonia is greater than the speed of exit therefrom so as to compensate for contraction of the fibres as a result of the treatment. 